This invention relates to an image pickup apparatus and method, an image processing apparatus and method, an image display system, a recording medium and a program, and more particularly to an image pickup apparatus and method, an image processing apparatus and method, an image display system, a recording medium and a program by which moving pictures can be displayed so as to exhibit a smooth movement of an object.
It is demanded to improve the signal processing technique and the driving technique for an image display element to improve the picture quality of a displayed image.
Generally, in order to improve the picture quality, the resolution of an image should be raised so as to make the texture of the display image finer. The amount of information of an image is represented in a unit called pixel which represents a dot which forms the image, and the number of pixels is represented by the numbers of dots in horizontal and vertical directions of the image like, for example, 800×600 or 1,024×768. As the number of pixels (dots) increases, the texture of the image becomes finer and the amount of information which composes the image increases.
A system which makes it possible to display an image with a high resolution is known and disclosed, for example, in Japanese Patent Laid-Open No. Hei 10-124024. According to the system, for example, two first and second display units are used, and in a normal single mode, an image is displayed on the first display unit whereas, in a multi mode, for example, the left half of an image is displayed on the first display unit while the right half is displayed on the second display unit. Consequently, in the multi mode, an image can be displayed with a doubled resolution compared with a system which uses only one display unit.
If the resolution is raised to display an image, since the amount of information which forms the image increases, the amount of data to be transferred to the first or second display unit increases, and consequently, it is demanded to increase the data transfer rate. Therefore, the system is configured such that the amount of data per one dot of the first and second display units is reduced and the disappearing data are converted by signal processing so that image data can be transferred without increasing the data transfer rate.
Further, the picture quality particularly of moving pictures can be improved by raising the frame rate which is a value representative of the number of times by which the screen is updated for one second.
For example, where a projector is used to project and display moving pictures to and on a screen, the projector scans a frame image line by line in a horizontal direction to display the frame image. Then, after all lines of the image of the frame are scanned, scanning of image data of a next frame is started, and moving pictures can be displayed thereby.
On the other hand, when moving picture data to be displayed are picked up, in order to compensate for an invalid portion of a light receiving section of a CCD camera or the like, a pixel shifting technique of displacing the image forming position of the CCD image sensor successively by 1/n the magnitude of one pixel of the CCD image sensor upon image pickup is sometimes used. The technique just described is disclosed, for example, in “An Introduction to the CCD Camera Technique”, Corona, 1997, pp. 109-111. This technique is used in a camera which picks up images at the same point of time using multiple plate image pickup elements or another camera wherein a single image pickup element or an optical system is oscillated to pick up images at different points of time.
As described hereinabove, the picture quality particular of moving pictures can be improved by raising the frame rate. However, in order to perform a display process in accordance with a high frame rate, a high processing speed is required for a drive circuit for driving the display element, and besides a high speed of reaction is required for a light amount modulation element for determining the intensity of the image. This is technically difficult and gives rise to an increase of the cost.
Further where two display units are used to display an image with a doubled resolution with respect to a system which uses a single display unit, although a technique for decreasing the amount of data per one dot of display so that the data transfer rate may not become high is already used, this technique does not increase the frame rate of moving pictures to be displayed. Accordingly, also in the system wherein two display units are used so that an image can be displayed with a high resolution, in order to display moving pictures which indicate a smooth movement of an object, it is necessary to raise the processing speed of the drive circuit for driving the display element and raise the speed of reaction of the light amount modulation element.
Further, conventional display apparatus use various frame rates, and usually, the NTSC system and the HD system use a frame rate of 60 Hz; the PAL system uses another frame rate of 50 Hz; and the cinema uses a further frame rate of 24 Hz. The frame rates mentioned exhibit a signification degradation of the moving picture quality such as a blur or a jerkiness. Besides, if it is tried to pick up images with higher frame rates as a countermeasure for the problem, the amount of information which can be recorded on the real time basis has been limited to such levels as those specified above from a limitation to the driving speed of image pickup elements such as a CCD image sensor or from a restriction in data transfer to a recording medium. Although a special high speed image pickup apparatus which uses a CMOS sensor has become available recently, the image pickup apparatus is expensive, and under present conditions, only a method can be taken to store image information obtained from the image pickup apparatus into a memory. Thus, the special high speed image pickup apparatus is disadvantageous in image pickup in that the recording time is short (for example, several tens seconds) and much time is required for transfer of data read out from the memory.